Polymorphisms in the FAS and FASL genes are associated with functional changes in the encoded proteins; among the polymorphisms studied, rs1800682 (FAS -670A/G) and rs5030772 (FASL -124A/G) were evaluated in the development of neoplasms [16,17] and autoimmune inflammatory diseases [18,19,20], respectively. The gene discussed is FAS; the disease is neoplasm.